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t e e h S e e l h s s 3 RA mm Rw .0E N HT. Cm .G RN M oww. H R DG YR H mL .E RN .m Env A M d 0 M o m No. 416,109. Patented Nov. 26, 1889,

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E. R. HYDE 8.-, R. G. HORNER.

MACHINBPOR @BINDING PLANE s-URPAGES.

Patented Nov. 26, 1889.

No. 416,109. d

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3 Sheets-Sheet 3.,' E. R. HYDE & R. C?. HORNBR. MAGHINB PoR GRINDING PLANE SURPAGBS.

Patented Nov. 26, 18819.

(NolMoael.)

l l l l I mim Q S UNITED STATES .PATENT OEEicE.

ELIVIN R. HYDE AND RICHARD C. HORNER, OF SPRINGFIELD, MASSACHU- SETTS, ASSIGNORS TO THE SPRINGFIELD GLUE AND EMERY W' HEEL COMPANY, OF SAME PLACE.

MACHINE FOR GRINDING PLANE SURFACES.

SPECIFICATION forming part of Letters Patent No. 416,109, dated November 26, 1889.

Anplication filed August 13, 1888. Serial No. 282,681. (No model.)

To @ZZ whom it may concern.-

Be it known that we, ELWIN R. HYDE and RICHARD C. l-IORNER, of Springfield, in the county of Hampden and Commonwealth of Massachusetts, have invented a new and useful Improvement in Machines for Grinding Plane Surfaces, of which the following is a specification, reference being had to the accompanying drawings, forming part thereof.

Our invention relates to that class of abrading-machines in which are comprised one or more revolving abrading wheels or tools, and a work-support for exposing,` the surface of the article operated upon to the action of said wheels or tools for the purpose of reducing said surface to a uniform plane, and it has especial reference to machines of this class in which the work-support is itself revolved in a plane at 'a right angle to the plane of revolution of the abrading wheels or tools.

The object of our invention is to increase the effective abrading capacity of such niachines, and also to combine therewith means whereby the adjustments of the several parts of the machine itself and the introduction of work thereto and its removal therefrom will be greatly facilitated and expedited.

To this end our invention consists in a machine comprising an abrading medium which has both a revolving and a reciprocatory movementand a plurality of revoluble worksupports mount-ed upon a common revoluble bed, whereby each of said work-supports can be moved to a position where the work carried thereby will be exposed to the action of the abrading medium.

Our invention furthermore comprises, certain details of construction hereinafter fully described, and particularly7 pointed out in the claims.

Referring to the drawings, in which like parts are designated by like letters in the several figures, Figure l is a side elevation of the machine, looking toward the left in Fig. Fig. 2 is a front elevation thereof. Fig. 3 is a vertical longitudinal section of the front portion of the frame of the machine and of the work-supporting devices. Fig. 4 is a plan view of the mechanisinfor reciprocating the cross-head which carries the abrading medium. Fig. 5 is a similar View of the mechanism for revolving the work-holding table, the outlines of the tables and their supporting-bed being indicated by broken lines. Figs. 6, 6, 6b, 6C, and 6d are detail perspective views of the devices by which the abrading medium is adj ustably supported. Fig. 7 is a View in perspective of one of the revolving tables which support the work. Fig. 8 is a cross-section thereof, taken upon line 8 8 of Fig. 7 Fig. 9 is a view in perspective of one of the jaws of the work -holding clutches. Fig. 10 is a vertical section thereof, taken upon line l0 l0 of Fig. 9.

The letter A designates the frame of the inachine,which frame terminates at the front end in a vertical cylindrical hub A', and at its rear end in an upright and slightly-overhanging arm A2, which arm and hub support, respectively, the abrading and work-holding mechanisms. Frame A is preferably made hollow in form to lessen its weight, and also to enable that portion thereof lying in front of arm A2 to be utilized as a reservoirforwater when the abrading medium is of the Wetgrinding class, which reservoir is designated by the letter A3 in Fig. 3.

As herein shown, the abrading medium is composed of two emery wheels B B of a corresponding diameter, which have a common revolving and laterally-reciprocating movement and a common vertical adjustment, and in addition to such common movements each of said wheels is preferably provided withA means whereby it can be independentljT adjusted both vertically and laterally. The means shown for securing these various movements of the abrading medium will be first described.

The upright arm A2 of the frame, which preferably curves slightly toward the front end of the frame, terminates in a vertical face of considerable arca, as shown, and projecting from said face are two vertical ribs a, the outer edge of each of which is undercut, as shown in Fig. at. i

The letter C designates a head-block, in the rear side of which is a vertical groove c, having undercut edges to receive the outer edges of the ribs a on arm A2, and thus retain the head-block upon the arm in such manner as to permit free vertical movement of the former. By making two ribs a upon the arm, instead of a single rib of the full width of groove c, the wearing-surface of said parts is materially reduced without weakening the connection between them.

Head-block C is provided at each end with arms c c2, projecting horizontally therefrom, the front faces of which arms are'flush with the front face of the block, and the rear faces of which are preferably provided with strengthening-ribs c3, as shown.

Projecting from the front face of the headblock and its arms is a rib c4, extending at a right angle to the groove c in the rear face of the block, the edges of which rib are undercut to receive the undercut edges of a groove d in the rear side of a cross-head D, whereby said cross-head is retained and permitted to have free lengthwise movement upon said block. Said cross-head D (shown in detailin Fig. 6) is preferably slotted, as shown at d, for the greater portion of its length, and is provided at its front side with a longitudinal rib cl2, having undercut edges to receive the edges of a groove e in the rear faces of two corresponding plates E E', and thereby adjustably retain said plates upon the crosshead.

Right and left hand screws cl3 d'* (see Fig. 6b) are mounted in a block d5, seated in the end of cross-head D and retained therein by means of screws do, as shown, or in any other convenient manner, said screws being provided with collars upon each side of said block,.whereby they are adapted to have a free revolving movement therein without endwise progression. Each of the plates' E E is provided upon its rear side with a projecting threaded hub e', which hubs, when the parts are assembled, project within the slot in the cross-head and receive, respectively, the threaded portions of screws (Z3 d4, whereby, by turning said screws by means of a wrench or permanent handle, said plates E can be adjusted independently toward and away from eachother upon said cross-head. Upon their front sides each of the plates E E is provided with a vertical rib c2, having undercut edges to receive the edges of vertical grooves fin the rear sides of two wheel-heads F F, one of which heads is shown detached in Fig. 6C. Adjusting-screws j", mounted in upwardly projecting brackets f2 on said wheel-heads in such manner as to revolve without endwise progression, are t-apped into the plates E E at their lower ends, and are preferably provided with the usual handles f3 at their upper ends, as shown. By means of said screws f either of the wheel-heads can be independently adjusted in a vertical direction upon the plates E E. Projecting from the front side of each of the wheel-heads F F are two arms f4, containing bearings for one of the shafts B2, which carry the abradingwheels B B', respectively.. .One of said abrading-wheels is suitably secured to the inner end of each of said shafts B2, and upon each of said shafts, bet-Ween its bearings f4, is secured a band-pulley l), by which revolving movement is transmit-ted to said shafts and abrading-wheels from a suitably-arranged counter-shaft.

It will be observed that by the means just described provision is made for independently adjusting the abrading-wheels both laterally and vertically, the former adjustment being for the purpose of gaging the distance between said wheels according` to the width or diameter of the work to be operated upon, and the latter adjustment being for the purpose of compensating for unequal wear of `said wheels by slightly depressing the one which wears away most quickly, should it become necessary to do so.

In addition to the two independent adjustments, the wheels B B have a common laterally-reciprocating movement with the crosshead upon head-block C, and also a common vertical movement with said head-block upon arm A2 of the frame, as hereinbefore stated,

and to the means for producing such common movements attention is next directed.

Upon the rear sides of arms c c2 of headblock C are secured by screws, as shown, or in any suitable manner threaded hubs ci", which hubs receive, respectively, right and left hand threaded vertical screw-shafts C', which shafts are mounted at their lower and upper ends in bearings c(i upon each side of the'frame of the machine. At their upper ends said screw-shafts carry bevel-gears c7, and mounted in bearings upon the top of arm A2 is a cross-shaft C2, carrying at each end bevel-gears cs, which mesh with said gears c7, and thereby transmit the motion of one of said screw-shafts to the other in a well-known manner. The screw shaft upon the right side of the frame, as seen in Fig. 2, is continued nearly to the bottom of the frame and carries at its lower end a bevel-gear c", which mcsheswith a bevel-gear 010 upon the rear end of a horizontal shaft G2, mounted in.

suitable bearings upon the side of the frame. Said shaft G3 extends to or nearly to the front end of the frame and at its front end is squared to receive a wrench, as shown, or may be provided with a suitable hand-wheel to enable said shaft to be revolved manually. Revolution of shaft C3 will, through the arrangement of the gears and the cross-shaft, as just described, impart a similar movement to both screw-shafts C in opposite directions, and by the movement of the threaded hubs c5 upon said screw-shafts head-block C, the cross-head, and wheels B B will be raised or lowered upon arm A2 as said shaft C3 is turned in one or the other direction. In order to counterbalance said block and the parts carried thereby, and thus render the vertical adjustment thereof, as just described,

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- very easy, we connect one end of a rope or `manner.

with cross-head D, as shown in Figs. 2 and l.

chain c thereto bymeans of an eye cl2, secured to the head-block midway between the ends of thc latter, and conduct said rope or chain over two pulleys cl3, mounted in brackets secured to arm A2, to the interior of said arm, where suitable weights are suspended thereon, as shown by broken lines in Fig. l.

The object of the common vertical adjust-l ment o f wheels B B', thus effected, is for the purpose of lowering said wheels upon and raising them from the work, and also to regulate their grinding action upon the surface of the work, and by the means just described a very delicate vertical adjustment of said wheels can be made with perfect ease.

The lateral reciprocating movement of wheels B B' is produced as follows: A horizontally-extending bracket G is rigidly secured to arm A2 of the frame near its upper end, which bracket is provided with bearings g for a horizontal worm-shaft G', carrying worm g' and cone-p Lilley g2. (See Fig. et.) Said bracket is also provided with bearings g3 for a vertical shaft G2, vthe upper end of which shaft passes loosely through said bearings and through a worm -gear g", which is mounted between said bearings, and which meshes with worm g'. A spline-andkey connection between shaft G2 and wormgear g4, as shown, compels said shaft and gear to revolve in unison, while permitting the former to move vertically within the latter. Said shaft G2 is mounted at its lower end in a bearing 7i of a bracket H, secured to the rear side of arm c2 of head-block C by screws passing through said bracket into a pad formed upon said arm, as shown by broken lines in Fig. 4, or in any other convenient manner. Collars secured upon said shaft above and below said bracket Il compel the former to follow the vertical movements of the latter as headblock C is moved up or down, and to the lower end of said shaft is secured a gearwheel g5, which meshes with a similar gearwheel g, secured to the lower end of a short vertical shaft G3, mounted in a bearing 7L' in said bracket H. At its upper end said shaft G3 carries a crank-disk Q7, having a crank-pin g8 adjustable toward and away from the center of said disk by a screw Q9, in the usual A link gw connects said crank-pin Motion being communicated to worm-shaft G' from a suitably-arranged counter-shaft through a belt and cone-pulley g2, said shaft will, through worm g', gear g4, shaft G2, and gear-wheels g5 gs, impart a uniform revolving movement to shaft G3 and crank-disk g7, and the latter, through link glo, will impart a horizontal reciprocating movement to the crossvhead and wheels B B', the amount of which reciprocating movement can be accurately gaged by the adjustment of crank-pin g8. The abrading-wheels B B receive their revolving movements by meaus'of belts connecting their pulleys 1 with a counter-shaft,

which belts will preferably be led overintermediate idler-pulleys, which are free to move lengthwise of their shafts, to enable the belts to follow the reciprocating movements of said wheels. By means of the compound revolving and reciprocating movement of the abrading-wheels thus secured their capacity for quickly reducing the surface of the work is greatly increased; but this desirable result is still further increased by the revolving movement which is imparted to the work itself in a plane at a right angle to the plane of revolution of said wheels, and to the means devised by us for supporting, and thus revolving, the work attention is now directed.

As hereinbefore stated, one of the objects of ou r invention is to combine with the means for holding and operating the' abrading medium, as shown and described, a plurality of revoluble work-holding mechanisms, each of which can be moved to a position to present the surface of the work held thereon to the act-ion of the abrading medium. By thus providing two or more of such work-holding mechanisms we are enabled to greatly expedite the operation of the machine, inasmuch as new work can be secured upon and finished work removed from those that are idle at the same time that the abrading medium is operating upon the work held by the one which is in operation. For the purpose Vof illustrating this feature of the invention we have shown two of these work-holding mechanisms, which are constructed as follows:

The letters I l designate two circular tables carried at the upper ends of short shafts t, said tables having the usual intersecting-slots, T-shaped in cross-section, within their upper surfaces, and having concentric bearing-surfaces t" on their lower surface, as shown in Figs. 7 and 8. The shafts i of said tables are mounted in vertical bearings within and upon opposite sides of the center of a bed K,which bed is mounted upon hub A' of the frame by means of a tubular stud 7c, projecting within said hub, as shown in Fig. 3, whereby said stud serves as a pivot about which as a center the bed is free to revolve horizontally. As shown, the bed is substantially oval in outline, and is provided upon its upper surface with concentric bearing-surfaces 71:', corresponding to those upon tables I, and is preferably provided around its edge with an upwardly-extending flange k2. The upper surface of the bed, with the exception of the horizontal bearing surfaces k', preferably slopes gradually and downwardly from its edge toward its center, where it is provided IOO IIO

with an opening extending through stud 7c,

as shown in Fig. 3, whereby the water used with a wet-grinding abrading medium, which falls upon said bed, is caused to seek said central opening in the latter and descends therethrough into the reservoir in frame A. The tables I are provided with downwardlyextending annular flanges t2, which overlapthe edges of the outer concentric bearing-surfaces Zo of the bed, as shown, and prevent the Water, particles of emery, dac., from working between the respective bearing-surfaces of the tables and bed, thereby avoiding a common clutches for engaging and holding the work.

Said clutch-es preferably consist of two orl more jaws I', (see Figs'. 9 and 10,) composed of a lower member, which is secured to the table by bolts with T-shaped heads located within the slots in the table, and an upper member movably secured upon said lower member and adj usted thereon by a screw 3, which is mounted in a bearing on the lower member and enters a nut secured to the upper member. Ve have shown the workingfaces of the jaws of said clutches as being formed upon the arc of a circle and concentric with the centers of the tables, thereby adapting them for .use in connection with circular work; but it will be understood that said working-faces will be formed to correspond with the character of work upon which the machine is to be used.

Upon the lower ends of shafts Z of the tables and beneath bed'` K are secured corresponding Worm -gears Z4, collars being lon v cated upon said shafts between said gears and the lower surface of the bed', to insure steadi- Y ness of movement to the shafts.

The letter L designates a worm-shaft,which is mounted at one end in a bearing Z, pivotally secured to a bracket L', projecting from frame A, in suoli manner that said bearing isfree to turn horizontally upon its pivot. Near its opposite end said shaft L is supported by a bearing Z', secured to a plate Z2, which plate rests upon a pad formed upon frame A, to which it is secured by bolts Z3, passing through slots Z4 in the plate, whereby said plate is permitted to have a limited sliding movement toward and away from hub A of the frame. Shaft L at its free endA carries a worin Z5, which is adapted to mesh with one of the gears Z4 of tables l when plate Z2 occupies its forward position, but which is moved to a position to clear said gear when said plate is moved to its rearmost position. N earits opposite end said shaft is provided with a bandpulley Z6, by which motion is transmitted to said shaft from a counter-shaft througha belt.

It follows from the construction just described that when either of the gears i* is in mesh with the revolving worm Z5 its table I and the work held thereon will be given a uniform revolving movement in a horizontal plane, and it follows, furthermore, that by moving said worm to a position to clear said gear the bed K can be revolved about its pivot to bring the opposite gear and table beneath wheels B B.

It is essential that means be provided for `locking the bed to prevent movement thereof while the abrading medium is operating upon the work carried by either of the tables l, and we have combined means for this purpose of arm A2. f with a socket Zas to receive the front end of l said bolt, so located upon said bed that when either of the tablesl is directly beneath wheels with the means for shifting plate Z2 and worm Z5 in such manner that both functions are performed by a single lever. Said lever (designated by the letter M) is pivoted at m to the side of frame A, its short arm extending upwardly to the plane of bed K and its long arm extending to the front end of the frame, where it terminates in a suitable handle, as shown.

To the end of the short arm of said lever is pivotall'y connected the rear end of a bolt m',

sliding within a sleeve m2, secured to the side Bed K is provided at each end B B one of said sockets will be opposite the end of said bolt. By moving lever M from the position shown by broken lines in Fig. l to that shown by full lines bolt m will be thrust forward to cause it to enter one of the sockets on the bed, and by moving said lever in the opposite direction said bolt will be withdrawn from its engagement with the bed. A lever N, pivot-ed at one end to frame A, as shown in Fig. 5, is connected at its opposite end by means of a link nto the short arm of lever M, and between Aits endsby means of a link n to plate Z2. It follows, therefore, that the same movement of lever M which withdraws bolt m from engagement with the bed will with- `draw worm Z5 from mesh with either of the gears /Z4,.and, conversely, that the same movement of said lever which restores said worin to mesh with one of said gears will project said bolt into one of the sockets of the bed, and thus rigidly hold said bed from movement. A standard m5, secured to the frame adjacent to the end of the long arm of lever M, is provided in its side next to said lever with a notch, as shown in Fig. 2, to receive the latter and retain it in the position shown by broken lines in Fig. l whenever it may be desired to do so.

As the abrading-wheels bear with a heavy pressure upon the work, and as the latter is supported upon bed K at one side of the central support of said bed, we provide the bed at each end with a downwardly-projecting bearing 7a4, in which is journaled an anti-friction roll Z55, and provide frame A with a shoulder a, upon which one of said rolls bears, as

shown in Figs. l and 3, in each operative po sition of the bed. By this means the downward pressure upon the bed during the operation of the abrading-wheels upon the work is distributed between shoulder d. and hub A', and undue strain upon the bed is avoided.

Vhen the abrading-wheels' employed are of the class known as wet-grinding wheels, we design to utilize a small centrifugal or other pump to raise water from the reservoir in frame A and carry it through suitably-arranged pipes to the surface of the wheels, whence it passes to the bed, and from thence back into the reservoir, as previously described. Aconstant circulation of the same water is thus effected, which is especially ad- IOO IIO

vantageous in locations where it is not convenient to connect the machine with water supply and'escape pipes. Te have notI shown said pump and water-conducting pipes, for the reason that their use is common to all of our wet-grinding machines, and because they form no part of our present invention.

For the purpose of affording access to the reservoir, the frame is provided with an opening a2, which opening is normally closed by a cover, as shown in Fig. Access to arm A2 of the frame is also afforded by a door a3 (shown in Fig. 2) in case it should be desirable to enter said arm for any-purpose.

The operation of the machine thus constructed is as follows: Presuming band-pulleys l) ZJ, g2, and Z to be connected by belt with the same or differentcounter-shafts, whereby revolving movement is transmitted to wheels B B and worin-shafts Gand L, wheels B B are adjusted laterally by means of screws d3 d4, to locate them at the proper distance apart with respect to the width or diameter of the work to be operated upon, the work itself is firmly clamped between the clutch-jaws of one of the tables I, bed K is Vmanually revolved to move said 'table and work beneath the abrading-wheels, lever M is moved to project bolt m into the adjacent socket of Vsaid bed and also to move worm Z5 into mesh with the gear i* of said table, and the machine is set in operation. The revolving and laterally-reciprocating abrading-wheels are now lowered upon the work by turning shaft C3, and are regulated as to their abrading action upon the sur- Aface of the work by means of said shaft, as

hereinbefore described. The work itself being revolved in a planeat a right angle to the plane of revolution of the abrading-wheels, the latter very rapidly reduce the surface of the former, and the lateral reciprocating movement of the wheels causes the surface operated upon to be a true plane. Vhen two abrading-wheels are employed, as shown, they will preferably be of different degrees of coarseness, so that one of them will perform the function of a finishing-wheel, and should one of said wheels wear away more rapidly than the other it can be depressed to compensate for such wear by means of its screw f. Either of the wheels B B', moreover, can be moved by one of the screws cl3 d4 to a position where it will be entirely clear of the work whenever it is desired to use but one of said wheels, thus enabling` the machine to operate as a single-wheel machine. While the abrading-Wheels are thus operating upon the work carried by one of the tables I, new work can be clamped upon the idle table ready to be moved under the wheels as soon as they have completed their first operation, whereby a great saving in time in feeding work to and `removing it from the machine is effected.

Bed K is balanced upon hub A of the frame in such manner that it can be revolved upon said hub with but slight exertion; but, if desired, any suitable anti-friction devices can be employed to increase its freedom of movement.

Having completed the operation upon the first piece of work, wheels B B are elevated slightly by turning shaft C3, lever M is moved from the position shown by full to that shown by brokenV lines in Fig. l, bed K is revolved to move the second table I beneath the wheels, said lever M is restored to its former position and wheels B B are lowered upon the new work, and the operation proceeds as before. The operation would be the same were the bed provided with more than two tables I, each being moved under the abrading-wheels in regular sequence.

The work for which the machine herein shown and described is especially designed is the grinding of the annular bearing-surfaces of valve-bodies and other similar circular work, in which the wheels B B operate at diametrically-opposite points upon the surface of said work; but it is adapted to operate equally well upon flat surfaces generally.

Vhile we have shown and described the abrading medium as consisting of emerywheels, it will be understood that we do not thereby wish to limit ourselves to the. use of such material, as it is obvious that the particular abrading material employed is not essentially related to the construction and operation of the machine itself. It is obvious, furthermore, that various modifications 0f the details of the construction shown and described can be made without departing from the spirit of our invention.

Having thus fully described our invention, what we claim, and desire to secure by Letters Patent, is

1. The machine for grindingplane surfaces herein described, comprising, in combination, a revolving and laterally-reci procating abrading medium and a plurality of revoluble work-supports mounted upon a common revoluble bed, whereby each of said work-supports can be moved to a position to present the surface of the work carried thereby to said abrading medium, substantially in the manner and for the purpose described.

2. The machine for grinding plane surfaces herein described, comprising, in combination, a revolving and lateraliy-reciprocatingI abra-ding medium,a revoluble bed 'having its plane of revolution at a right angle to that of said abrading medium, a plurality of revoluble work-supports mounted upon said bed, each of which work-supports is provided with a worin-gear, and a worin-shaft mounted in movable bearings, whereby the worm carried thereby can be moved into and out of engagement with the gears upon said work-supports, arranged and operating substantially in the manner described.y

3. In a machine for grinding plane surfaces, the combination of the following instrumentalities, viz: a substantially-horizontal frame terminating at one end in an upright arm, a

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head-block secured to and vertically adjustable upon said arm, a horizontally-movable cross-head mounted upon said head-blocks, a wheel-head adj ustably secured to said crosshead, said wheel head having journaled thereon a shaft carrying an abrading-wheel, a crank-shaft having link-connection with said cross-head, whereby -revolution of the former will produce a reciprocating movementof the latter, a `worm-shaft carrying a band-pulley, intermediate gearconnections between the worm upon said shaft and said crank-shaft, and a revolving` work-support mounted upon said frame beneath the plane of said abrading-wheel, arranged and operating substantially as set forth.

4. In a machine for grinding plane surfaces,

' a substantially-horizontal frame terminating at one end in an upright arm, a vvertically-adj ustable head-block mounted upon said arm, a longitudinally-reciprocatin g cross-head carried by said head-block, two vertically and horizon tally adjustable wheel-heads mounted upon said cross-head, a shaft carrying an abrading-wheel and a band-pulley journaled in each of `said wheel-heads, a bed mounted upon a Vertical axis upon said frame, and a plurality of revolving work-su pports mounted upon said bed, arranged and operating substantially as set forth.

5. In a machine for grinding plane surfaces, frame A, having upright arm A2 at one end thereof, head-block C, adjustably mounted upon said arm, cross-head D, mounted to slide transversely upon said head-block, said crosshead being slotted, as shown at d', and having adj Listing-screws (Z3 (Z4, mounted to revolve Without endwise progression in one end thereof and extending into said slot, plates E E', movably mounted upon said cross-head, each of said plates having a nut c', extending into the slot in the cross-head and receiving one of said screws (Z3 cZi, wheel-heads F li", vertically movable upon said plates E E', respectively, adjusting-screws j", mounted upon said wheel-heads and tapped at one end in said plates, and shafts B2, each carrying a band- `pulley and an abrading-wheel journaled in said wheel-heads, arranged and operating substantially as described, whereby provision is made for independently adjusting said wheel-heads both vertically and horizontally upon said cross-head, in combination with bed K, revolubly mounted upon said frame, and tables I, revolubly mounted upon said bed, substantially as set forth.

6. In a machine for grinding' plane surfaces, frame A, having arm A2 at one end thereof, head-block C, supporting the revolving and laterally-reciprocating abradin g medium and having a vertically-sliding connection with said arm A2, threaded hubs c5, secured to said head-block, vertical screw-shafts C C', havin g right and left hand threads engaging the threads in said hubs, each of said shafts having at its upper end a bevel-gear c7 and one of said shafts having at its lower end a bevelgear c, cross-shaft C2, having at each end bevel-gears es, meshing with the gears e7 of said screw-shafts, and horizontal shaft C3, having at one end bevel-gear 010, meshing with the gear c at the lower end of. one of said screw-shafts and having its opposit-e end provided with suitable means whereby it can be revolved manually, combined and operating substantially as and for the purpose described. j

7. In a machine for grinding plane surfaces, frame A, having'at one end upright arm A2, supporting the abrading medium and having at its opposite end cylindrical hub A, bed K, resting upon said hub and having a central stud k, projecting within the latter, a plurality of work-supporting tables I, mounted upon said bed by means of short vertical shafts t, passing through the latter and carrying worm-gears t4 at their lower ends, a worm-shaft L, mounted at one end in a pivoted bearing Z and near its opposite end in a bearing Z, secured to a sliding plate Z2, said shaft carrying band-pulley ZG and worm Z5, and means, substantially as described, for moving said plate Z2 toward and away from hub A', combined and operating substantially as described, whereby said worin can be moved into and out of engagement with either of the worm-gears connected with said worksupporting tables.

8. In a machine for grinding plane surfaces, the combination, with frame A, having revolubly-mounted thereon bed K, carrying tables I, said tables having vertical shafts t' and worin-gears Z4 at the lower ends of said shafts, of a locking device on said frame to engage said bed and prevent movement thereof, sliding plate Z2, mounted upon said frame and supporting one end of wormshaft L, carrying worm Z5, a lever, as M, fulcru med upon said fram e, andintermediate connections, substantially as described, between said lever, sliding plate Z2, and the locking "device, whereby movement of said lever will impart movement to said plate and locking device simultaneously, substantially as and for the purpose set forth.

9. In a machine for grindii'ig plane surfaces, the combination, with frame A, bed K, hav ing a horizontal revolving movement upon said frame, and tables I, having a horizontal movement upon said bed, of worm-gears 714, operatively connected with said tables, wormshaft L, mounted at one end in a p ivoted bearing Z and near its opposite end upon sliding plate Z2, elbow-lever M, pivoted upon the side of frame A, locking-bolt m', connected at its rear end to the short arm of said lever, sockets 7a3 upon bed K, to receive the front end of said bolt, lever N, pivoted at `one end to frame A, link n, connecting the opposite end of said lever with the short arm of lever M, and link n', connecting said lever N between its ends with sliding plate Z2, arranged and operating substantially as and for the purpose set forth.

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operative position, combined and operating substantially as and for the purpose set forth.

1l. In a machine for grinding plane surfaces, hollow frame A, having at one end up* right arm A2 and at its opposite end cylindrical hub A', communicating with reservoir A3 in said frame, in combination with bed K, having a central tubular stud 7c., projecting within said hub A', said bed having an upwardly-extending ange 7a2, extending around its outer edge, a central opening communicating with the bore of stud 7c and horizontal annular bearing-surfaces 7c', and having its upper surface, with the exception of said bearing-surfaces, inclined downwardly from the edge to the central opening thereof, and tables I I, supported upon the bearing-surfaces of said bed, substantially as and for the 3o purpose described.

ELWIN R. HYDE. RICHARD C. HORNER. Witnesses:

XV. H. CHAPMAN, T. M. BROWN. 

